1. Field of the Invention:
This invention relates to a phosphorescent fiber reinforced plastic (FRP) article and to a process for making such an article.
2. Description of the Related Art:
Phosphorescent coated textiles and fabrics are known, as exemplified by U.S. Pat. No. 3,291,668 to Goldstein which teaches phosphorescent particles on a textile substrate and then pressure laminating a clear plastic outer layer. The purpose of the invention is to provide an improved phosphorescent coated textile material, particularly for the foot covering art.
U.S. Pat. No. 4,663,214 to Coburn teaches an improved phosphorescent material decorative in visible light, and a process for making the same. The phosphorescent material comprises a support layer of opaque material, an intermediate layer of phosphorescent material in combination with an over layer of substantially iridescent material, and a top surface layer of protective material.
U.S Pat. No. 4,211,813 to Gravisse et al. teaches a photoluminescent flexible sheet material having an enhanced permeability to water vapor. The photoluminescent flexible sheet comprises a flexible substrate having at least one coating film comprising at least one synthetic resin having dispersed therethrough a photoluminescent complex, said complex comprising at least one phosphorescent metal sulphide and an organic substance which absorbs radiant energy and emits it in a wavelength lying within the phosphorescent metal sulfide. The purpose of the invention is to provide safety and protective garments.
U.S. Pat. No. 4,781,647 to Doane teaches extruding a thermoplastic polymer containing a mixture of phosphorescent particles. The resultant fibers are then used to make doll hair which glows in the dark after being submitted to a source of energy.
None of these patents teaches applying a phosphorescent material to a surface veil, fabric or mat and then using the resultant product to provide a phosphorescent material on the surface of a molded article formed from a fiber reinforced plastic material. Incorporating phosphorescent material technology into the fiber reinforced plastic material manufacturing processes is not taught by the prior art.
The term fiber reinforced plastic (FRP) defines a material obtained by a series of processes in which fibrous materials (glass, aramid, graphite, etc.) are combined with resinous materials, such as thermosetting or thermoplastic resins, to make a shape that is stronger than the resin itself. Thermosetting resins encompass a wide range of materials including, but not limited to, polyesters, vinyl esters, bisphenol, epoxies, etc. A thermosetting resin is one which cures or polymerizes and cannot be melted and reshaped with the application of heat.
In fabricating a thermoset FRP part, typically the fiber reinforcement is saturated or wet-out with a liquid thermosetting resin. After being wet-out, the saturated reinforcement is then shaped either manually or mechanically into the form of the finished article such as a part. Once formed, the shape is then allowed to cure via the polymerization of the thermosetting resin. This is accomplished by a specific time and temperature relationship based on the formulation of the resin.
Pultrusion is a thermoset FRP process wherein reinforcements and surfacing fabrics such as mats or veils are drawn through a resin bath to achieve wet-out. Then they are pulled through a mold in the shape of the desired article. Typically, the mold is heated to accelerate the polymerization.
Contact molding or open molding is another FRP process. Resins and reinforcements are manually (hand lay-up) or mechanically (spray-up) deposited on an open mold surface. The mold surface is preferably previously coated with a gel coat and is provided with a surfacing fabric such as a mat or veil. Once the required amounts of reinforcements and resin have been deposited on the mold, the laminate is worked with rollers, brushes or squeegees, usually manually, to remove any trapped air and thoroughly saturate or wet-out the reinforcements with resin. Once this is completed, the laminate is allowed to cure, normally at ambient temperature.
Resin transfer molding (RTM) and structural reaction injection molding (S-RIM) are two similar closed mold FRP processes in which the required reinforcement package, including a surfacing fabric such as a mat or veil, is placed in one-half of the mold cavity, usually the bottom half. Once properly positioned, the top half of the mold is closed the bottom half thereof and secured in place. Next, the resin is injected slowly under minimal (e.g 50 psi) pressure in RTM or rapidly under high pressure (e.g. 2000 psi) in S-RIM. The mechanical pumping and resulting pressure causes the air to be flushed out of the mold cavity and the resin to saturate or wet-out the reinforcement. The resin impregnated reinforced article is then allowed to cure.
Compression molding is also a FRP mold process. In this process, the reinforcement package including surfacing fabric (mats or veil) and the resin are placed on one-half, usually the bottom half, of the mold cavity. Once properly positioned, the top half of the mold is mechanically closed on the bottom half using a press which compresses the reinforcement package and resin under pressure (from 50 to 1500 psi) to flush out the air and thoroughly saturate or wet-out the reinforcement package with resin. It is then cured normally with the assistance of heat.
Filament winding is a FRP process in which reinforcements, normally continuous rovings, are saturated with resin, normally by pulling them through a pan or bath containing the resin. The reinforcements are then wound on a rotating mandrel in a specific pattern. The mandrel may or may not have been previously covered with a resin impregnated surfacing fabric. An outer layer or outer layers of surfacing fabric may be wrapped over the resin impregnated reinforcement when required. Once the required amount of resin, reinforcements and surfacing fabrics are properly placed on the mandrel, the laminate is allowed to cure with or without the assistance of heat.
Continuous panel process is a FRP process for making continuous flat and/or shaped, e.g. corrugated, panels. It involves depositing a resin on a carrier film which then passes under a reinforcement deposition area. Various types of reinforcement are then applied to the film of resin. The reinforcement and resin then go through a compaction section where a series of belts, screens, or rollers force air out and thoroughly saturate or wet-out the reinforcement with resin. A surfacing fabric such as mat or veil is then placed on the surface of the resulting saturated material and the fabric is allowed to saturate with resin. A carrier film is then applied to the top surface of the resulting article which is passed through a curing station where the resin cures normally with the assistance of heat. Once cured, the carrier film is removed and the article is cut to the desired length.
Previous attempts to add a phosphorescent material directly to a resin system have been unsuccessful, mainly due to the settling away of the phosphorescent material from the surface of the final article. This was due to the fact that phosphorescent materials have a relatively high density or specific gravity of e.g. 3.85-4.50, whereas the resin mix generally has a relatively low density or specific gravity of, e.g., 1.15-1.40. When put in the resin mix, the phosphorescent materials tend to sink to the bottom of the resin tank and/or wet-out pan. Little or less of the phosphorescent materials, therefore, become attached to the reinforcements or, more particularly, remain on the surface of the molded profile. Since the resin mixture is usually opaque due to the incorporation of fillers, any phosphorescent materials not on the surface would tend to be shielded from exhibiting their afterglow properties.
Putting the phosphorescent materials directly into the resin mix has not solved the problem due to the overall opacity of the system. The resin mixtures usually contain ten to forty percent by weight of a filler. This causes the mix to be relatively opaque and prevents the phosphorescent materials from being charged by incoming light which, in turn, prevents the glow from being visible.